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  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous and successive colour contrast expressed in “slow” phototactic behaviour of walkingDrosophila melanogaster (1979)
    Springer
    Journal of comparative physiology 130 (1979), S. 161-171 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A behavioural paradigm, the “fly balance” (Fig. 1), allows continuous recording of the position of a walking fly in a Plexiglas tube (Fig. 2). This apparatus was used to study elements of “slow” phototactic behaviour ofDrosophila melanogaster wildtype and some of its mutants. Lights of varying intensity and spectral composition were presented to the two ends of a Plexiglas tube (Fig. 3). The influence of the light stimuli on the walking behaviour and on the mean position of the flies relative to the light sources was evaluated. If at both ends of the test tube strong UV-lights (375 nm) of equal intensity were presented simultaneously, the addition of visible light (λ〉415 nm) at one end of the tube led to a preference of wildtype flies for the pure UV-light (Fig. 10). The “attractiveness” of a UV-light at one end of the tube was enhanced by a visible light present at the opposite end (Figs. 8, 9). These experiments are interpreted as demonstrating the perception of simultaneous colour contrast by flies. In experiments where lights of different wavelengths were presented successively it became evident that the attraction towards UV-light was strongest shortly after switching from visible light (λ≧425 nm) to UV-light (Fig. 11 a, b). A 1 s exposure to visible light was sufficient to enhance subsequent attraction towards UV-light (Fig. 13). This adaptational effect of visible light was only observed at high UV-intensities (Fig. 14). In UV-light it decreased at a rate which was not positively correlated to the UV-intensity (Fig. 15). This phenomenon of successive contrast confirms the conclusion that UV-light and visible light are perceived as different colours byDrosophila melanogaster wildtype. The colour adaptation effects may enable the visual system of the fly to achieve some colour constancy. Selective adaptation at the photopigment level can be excluded as the sole origin of the described phenomena. The data support the notion of photopic and scotopic vision being present in flies (Fig. 14), however, this distinctioncannot be accounted for by the photoreceptors alone. Mutants deficient in certain receptor types corroborate the idea that centraland peripheral retinula cells are functional under photopic light conditions (Figs. 6, 10, 14).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611050
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  • 2
    Electronic Resource
    Electronic Resource
    T-maze phototaxis ofDrosophila melanogaster and several mutants in the visual systems (1977)
    Springer
    Journal of comparative physiology 116 (1977), S. 209-225 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary T-maze phototaxis ofDrosophila melanogaster and several of its mutants was investigated as function of the light illuminating the mazes. For visible light the response curves of thewildtype are quite complex and nonmonotonic functions of the light intensity. The data are interpreted as a result of an interaction between visual subsystems: the system which receives inputs from receptor cells R1-R6 is inhibited by the system of receptor cells R7 and R8, probably by R8 alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605403
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  • 3
    Electronic Resource
    Electronic Resource
    Habituation and sensitization of the landing response ofDrosophila melanogaster (1981)
    Springer
    Naturwissenschaften 68 (1981), S. 332-332 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01047481
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  • 4
    Electronic Resource
    Electronic Resource
    Light induced modification of phototactic behaviour ofDrosophila melanogaster wildtype and some mutants in the visual system (1977)
    Springer
    Journal of comparative physiology 118 (1977), S. 261-271 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary After exposure to blue light for several hoursDrosophila melanogaster wildtype shows a phototactic behaviour in the “T-maze” and in the “choice tube” closely resembling that of mutants defective in receptor cells R1–R6. Exposure to yellow light of an intensity of 0.5 W/m2 reverts this behavioural modification within a period of 1 to 2h. The behavioural analysis correlates with the long lasting afterpotentials in electroretinograms ofwildtype Drosophila after prolonged exposure to blue light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611827
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  • 5
    Electronic Resource
    Electronic Resource
    A quantitative theory of transfection in B. subtilis (1975)
    Springer
    Molecular genetics and genomics 141 (1975), S. 121-145 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A theory of transfection is developed which describes three different types of experiments in transfection: The concentration dependence of transfection, transfection with marker rescue, and the mapping function in transfection crosses. The theory is applicable to transfection systems exhibiting quadratic or higher order dose response (SPP1, SP50, SP82). It pictures the essential process in transfection as follows: transfecting DNA molecules, having suffered inactivating events during uptake or intracellularly, have to recombine prior to replication under elimination of these lesions. The probability for recombination, successful in this sense, is calculated as a function of the number of DNA molecules within the competent cell, the mean number of inactivating events per DNA molecule, and the crossover probability per nucleotide. Under the assumption of random distribution of inactivating events over the population of DNA molecules and homogeneous crossover probabilities the theory explains on a quantitative basis a number of experimental observations in transfection, as for instance the relative efficiencies of different helper phage in transfection with marker rescue, the third order concentration dependence in SP50 transfection, and the high recombination frequencies observed in transfection crosses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267679
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  • 6
    Electronic Resource
    Electronic Resource
    The optic lobe of Drosophila melanogaster. I. A Golgi analysis of wild-type structure (1989)
    Springer
    Cell & tissue research 258 (1989), S. 441-475 
    Details
    ISSN: 1432-0878
    Keywords: Optic lobe ; Neurons ; Cell types ; Structurae mutanto ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Golgi studies of the neurons in the optic lobes of Drosophila melanogaster reveal a large number of neuronal cell types. These can be classified as either columnar or tangential. Columnar elements establish the retinotopic maps of the lamina, medulla, and lobula-complex neuropiles. They are classified according to the position of their cell bodies, the number, width, and level of their arborizations, and their projection areas. Tangential elements are oriented perpendicularly to the columns. The arborizations of different tangential neurons are restricted to different layers of the optic neuropiles, within such layers their dendritic fields may span the entire retinotopic field or only part of it. The abundance of cell types inside each of the columnar units of the optic lobe is discussed with regard to its possible functional significance. By means of their stratified arborizations the columnar neurons form what appear to be multiple sets of retinotopically organized parallel information processing networks. It is suggested that these parallel networks filter different kinds of visual information and thus represent structurally separated functional subunits of the optic lobe. Such a parallel organization of visual functions increases the sites for function-specific gene actions and may explain the behavioral phenotypes of recently isolated structural mutants of the optic lobe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218858
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  • 7
    Electronic Resource
    Electronic Resource
    Neuronal architecture of the central complex in Drosophila melanogaster (1989)
    Springer
    Cell & tissue research 257 (1989), S. 343-366 
    Details
    ISSN: 1432-0878
    Keywords: Central complex ; Golgi impregnation ; Neurotransmitters ; Protocerebrum, insect ; Immunocytochemistry ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary On the basis of 1200 Golgi-impregnated brains the structure of the central complex of Drosophila melanogaster was analyzed at the cellular level. The four substructures of the central complex — the ellipsoid body, the fanshaped body, the noduli, and the protocerebral bridge — are composed of (a) columnar small-field elements linking different substructures or regions in the same substructure and (b) tangential large-field neurons forming strata perpendicular to the columns. At least some small-field neurons belong to isomorphic sets, which follow various regular projection patterns. Assuming that the blebs of a neuron are presynaptic and the spines are postsynaptic, the Golgi preparations indicate that small-field neurons projecting to the ventral bodies (accessory area) are the main output from the central complex and that its main input is through the large-field neurons. These in turn are presumed to receive input in various neuropils of the brain including the ventral bodies. Transmitters can be attributed immunocytochemically to some neuron types. For example, GABA is confined to the R1–R4 neurons of the ellipsoid body, whereas these cells are devoid of choline acetyltransferase-like immunore-activity. It is proposed that the central complex is an elaboration of the interhemispheric commissure serving the fast exchange of data between the two brain hemispheres in the control of behavioral activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261838
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  • 8
    Electronic Resource
    Electronic Resource
    Activity labeling patterns in the medulla of Drosophila melanogaster caused by motion stimuli (1992)
    Springer
    Cell & tissue research 270 (1992), S. 25-35 
    Details
    ISSN: 1432-0878
    Keywords: 2-Deoxyglucose ; Visual system ; Visual pathways ; Neuronal activity labeling ; Motion detection ; Neuroanatomy ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We quantitatively describe 2-deoxyglucose (2-DG) neuronal activity labeling patterns in the first and second visual neuropil regions of the Drosophila brain, the lamina and the medulla. Careful evaluation of activity patterns resulting from large-field motion stimulation shows that the stimulus-specific bands in the medulla correspond well to the layers found in a quantitative analysis of Golgi-impregnated columnar neurons. A systematic analysis of autoradiograms of different intensities reveals a hierarchy of labeling in the medulla. Under certain conditions, only neurons of the lamina are labeled. Their characteristic terminals in the medulla are used to differentiate among the involved lamina monopolar cell types. The 2-DG banding pattern in the medulla marks layers M1 and M5, the input layers of pathway p1 (the L1 pathway). Therefore, activity labeling of L1 by motion stimuli is very likely. More heavily labeled autoradiograms display activated cells also in layers M2, M9, and M10. The circuitry involved in the processing of motion information thus concentrates on pathways p1 and p2. Layers M4 and M6 of the distal medulla hardly display any label under the stimulus conditions used. The functional significance of selective activity in the medulla is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381876
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  • 9
    Electronic Resource
    Electronic Resource
    Genetic dissection of the anterior optic tract of Drosophila melanogaster (1983)
    Springer
    Cell & tissue research 231 (1983), S. 551-563 
    Details
    ISSN: 1432-0878
    Keywords: Visual mutants ; Anterior optic tract ; Independent gene actions ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy shows that in wild-type Drosophila melanogaster the anterior optic tract (AOT) is formed by about 1260 fibers in males and slightly fewer in females. Golgi staining suggests that most AOT fibers connect the lobula with different regions of the central brain. In the sine oculis (so) and small optic lobes (sol) mutants the number of axons is drastically reduced, by 58% in sol and by 35% in so. In the double mutant sol:so there is a loss of up to 83% of the fibers in the AOT. Approximately half of the remaining 220 fibers form a well defined subbundle of very thin axons which is identifiable in wild type as well as in both single mutants. The fibers of this subbundle neither originate nor terminate in the visual ganglia: instead, they connect two different central brain regions. It is concluded that the combined action of the sol and so mutations abolishes more than 90% of the fibers of visual origin or destination in the AOT. Quantitative analysis of electron micrographs shows that the so and sol mutations act independently on nearly exclusive subsets of axons in the AOT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218113
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  • 10
    Electronic Resource
    Electronic Resource
    Neuronal architecture of the antennal lobe in Drosophila melanogaster (1990)
    Springer
    Cell & tissue research 262 (1990), S. 9-34 
    Details
    ISSN: 1432-0878
    Keywords: Antennal lobes ; Antennal glomeruli ; Antennal afferents ; Maxillary afferents ; Antennal interneurons ; Computer reconstruction ; Golgi impregnation ; Backfilling ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Computer reconstruction of the antennal lobe of Drosophila melanogaster has revealed a total of 35 glomeruli, of which 30 are located in the periphery of the lobe and 5 in its center. Several prominent glomeruli are recognizable by their location, size, and shape; others are identifiable only by their positions relative to prominent glomeruli. No obvious sexual dimorphism of the glomerular architecture was observed. Golgi impregnations revealed: (1) Five of the glomeruli are exclusive targets for ipsilateral antennal input, whereas all others receive afferents from both antennae. Unilateral amputation of the third antennal segment led to a loss of about 1000 fibers in the antennal commissure. Hence, about 5/6 of the approximately 1200 antennal afferents per side have a process that extends into the contralateral lobe. (2) Afferents from maxillary palps (most likely from basiconic sensilla) project into both ipsi-and contralateral antennal lobes, yet their target glomeruli are apparently not the same as those of antennal basiconic sensilla. (3) Afferents in the antennal lobe may also stem from pharyngeal sensilla. (4) The most prominent types of interneurons with arborizations in the antennal lobe are: (i) local interneurons ramifying in the entire lobe, (ii) unilateral relay interneurons that extend from single glomeruli into the calyx and the lateral protocerebrum (LPR), (iii) unilateral interneurons that connect several glomeruli with the LPR only, (iv) bilateral interneurons that link a small number of glomeruli in both antennal lobes with the calyx and LPR, (v) giant bilateral interneurons characterized by extensive ramifications in both antennal lobes and the posterior brain and a cell body situated in the midline of the suboesophageal ganglion, and (vi) a unilateral interneuron with extensive arborization in one antennal lobe and the posterior brain and a process that extends into the thorax. These structural results are discussed in the context of the available functional and behavioral data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327741
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